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New York (CNN)A team of senior-level FBI agents with decades of experience in long-term criminal and public corruption cases are handling the federal civil rights investigation into the controversial chokehold death of an unarmed black man by a white police officer, two law enforcement sources said Tuesday.

The New York-based agents have come together in recent weeks following a December grand jury decision to not indict the police officer, the sources told CNN.

The goal is a "fresh look" into the July death of Eric Garner at the hands of police Officer Daniel Pantaleo, in a case that led to anti-police demonstrations throughout the nation, a senior law enforcement official said.

The veteran investigators include an agent from the white-collar crime division who specializes in long-term criminal investigations, a supervisor in the public corruption unit and an agent who investigated the infamous 1997 police torture case involving Haitian immigrant Abner Louima, the source said

The investigation, which began in earnest after a grand jury declined to indict the officer, will look at everything from the actions of the responding officers and paramedics on the Staten Island street where Garner died to the role NYPD training may have played in the death, according to the source. The New York City Police Department prohibits chokeholds.

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"We want ... to take a fresh look," the senior official said.

Pantaleo's attorney, Stuart London, said the agents will find "there was no willful conduct with the specific intent to violate a federally protected right."

"This was a simple street encounter and race wasn't an issue," he said.

During Garner's fatal police encounter on July 17, he raised both hands in the air and told the officers not to touch him. Seconds later, a video shows an officer behind Garner grab him in a chokehold and pull him to the sidewalk, rolling him onto his stomach.

"I can't breathe! I can't breathe!" Garner said repeatedly, his cries muffled into the pavement.

As part of the federal investigation, FBI agents have visited the scene of Garner's death. They're also interviewing witnesses as well as reviewing witness testimony, the senior official said. The investigation is overseen by the federal prosecutor's office in Brooklyn.

The agents will also look over evidence from the NYPD's internal affairs investigation and may ask to interview officers and emergency medical technicians who responded, the official said.

Another aspect of the probe will be whether a chokehold was in fact used in restraining Garner, the senior official said.

The cause of Garner's death was "compression of neck (chokehold), compression of chest and prone positioning during physical restraint by police," the medical examiner's office has said. The death was ruled a homicide.

The case became emblematic of longstanding tensions between police and minority communities, especially given that the majority of people stopped under the NYPD's former "stop-and-frisk" police policy were African-American or Hispanic. A federal court ruled that stop-and-frisk was unconstitutional and tantamount to racial profiling.

Photos:Protests after Eric Garner grand jury decision

Photos:Protests after Eric Garner grand jury decision

Los Angeles Lakers' Kobe Bryant, center, warms up before an NBA basketball game against the Sacramento Kings on Tuesday, December 9, in Los Angeles. The team wore "I Can't Breathe" shirts during warm-ups in support of the family of Eric Garner. Since a grand jury declined to indict a New York police officer in the death of Garner, demonstrators across the country have taken to the streets to express their outrage. Garner, a 43-year-old asthmatic, died in July after he was put in a chokehold by the officer, Daniel Pantaleo.

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Photos:Protests after Eric Garner grand jury decision

Protesters gather in front of the Barclays Center during an NBA game in New York on Monday, December 8.

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Police clash with demonstrators at the entrance of a Target near the Barclays Center on December 8.

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Seven-year-old Elijah Owens, left, stands by people participating in a "die-in" demonstration outside the Philadelphia Eagles' stadium in Philadelphia on Sunday, December 7.

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People protest in the streets of Chicago on December 7.

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Demonstrators retreat in Berkeley, California, after police deploy tear gas during a protest that turned violent before dawn on December 7.

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A police officer in Berkeley clashes with a protester on December 7.

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A police officer raises a shotgun toward the crowd in Berkeley on Saturday, December 6.

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People in Los Angeles lie down during a "die-in" on Hollywood Boulevard on December 6.

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Police stand guard as protesters participate in a "die-in" December 6 at Grand Central Station in New York.

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Protesters shut down all eastbound and westbound lanes on Interstate 195, which links Miami Beach to the mainland, on Friday, December 5.

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Photos:Protests after Eric Garner grand jury decision

Demonstrators march through the Loop in Chicago on December 5.

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Protesters block an intersection in downtown Washington on December 5.

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Demonstrators march through a Macy's in Manhattan before staging a "die-in" at the iconic department store on December 5.

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Police make an arrest as protesters march through Manhattan early on December 5.

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Police officers form a line with demonstrations under way in Oakland, California, on Thursday, December 4.

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A demonstrator gets arrested during a protest in New York on December 4.

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Police detain a protester in New York on December 4.

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Demonstrators gather in New York's Foley Square on December 4.

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Police officers in New York staff a barricade at a Brooklyn Bridge exit ramp on December 4.

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Demonstrators march across the Brooklyn Bridge on December 4.

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"Black Lives Matter" is written across the cheek of Samaria Muhammad as she chants with fellow protesters in Atlanta on December 4.

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Demonstrators block the entrance to the Lincoln Tunnel in New York on Wednesday, December 3.

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Protesters lie down in Grand Central Station on December 3.

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A demonstrator cries at a protest in Philadelphia on December 3.

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Demonstrators block traffic on Interstate 395 in Washington on December 3.

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A woman speaks during a demonstration in Oakland on December 3.

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Police officers stand guard in New York's Times Square on December 3.

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Protesters rally near Rockefeller Center during a ceremony to light the Rockefeller Center Christmas Tree in New York.

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Protesters face off with police in Oakland.

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Demonstrators lie in the streets of St. Louis on December 3.

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Garner's death led to demonstrations around the city and came weeks before the racially charged police shooting of unarmed teen Michael Brown in Ferguson, Missouri. Separate grand jury decisions declining to prosecute police officers in connection with both deaths sparked national protests that sometimes involved clashes with police.

After the death, Pantaleo was put on modified assignment and stripped of his badge and gun amid the investigation, and the NYPD commissioner ordered an extensive review of training procedures.

Two lawsuits have previously been filed against Pantaleo. The plaintiffs in both suits allege false arrest, unlawful imprisonment, civil rights violations and other charges.

One suit from 2013 was dismissed in January 2014, while the second, from February 2014, remains open.